I don't think something as personal as genitals is anyone's business unless there's going to be intimacy. What do they need to know for? They don't, its not like they are going to have to face it everyday. In fact just like anyone else they are most likely never going to see or interact with it at all, so it doesn't matter what it is. Of coarse if some do know and suspect that you aren't really the same gender as them and you happen to use the same public restroom, this can make them very uneasy, the whole not knowing, they may have fears of you being a pervert or that you could sometime if the opportunity arose do something to hurt them when alone, particularly in the restroom with them. I've known ones that knew what I was, and each time that I would enter the restroom to go, or even if I was just washing my hands, they'd get out as quickly as possible, because again, they either knew I didn't have the same parts as them or didn't know and the uncertainty scared them. But other than the whole restroom thing, if those around you suspect or know that you are transgendered, and even if they may at times have curiousities about what may be between your legs or how you pee or get it on with another, its as much as none of their business just as it would be for anyone else without gender issues, though I do know some people, groups of guys or girls will occasionally talk about stuff like that, but if one doesn't want to that's their preference, one shouldn't have to feel like they have to be pressured into anything they don't want to talk about or show off. Keep your privates private unless its really absolutely necessary to explain yourself, and even still, it shouldn't be, ever, the transgendered thing maybe yes to those that need to know, but no one needs to know the very details of what part you have.